override OnDrawItem (CheckedListBox)

Question

I have a problem with customized CheckedListBox class. I've got the code that uses custom ComboBox class with override OnDrawItem (to include pictures). My goal is to change appearance so that the items appear in CheckedListBox class (also with override, to include pictures) instead of custom ComboBox. The problem is that the pictures are not showing correctly: they don't show at all until I click on the item and hold the mouse, or scroll the listbox... Also, checked items stay checked even after I uncheck them in code during runtime (only visually, logically they are OK). Any idea what's going on?

public class CategoryCheckBoxListImagified : System.Windows.Forms.CheckedListBox
{
   // other stuff....
   // ...

    protected override void OnDrawItem(DrawItemEventArgs e)
    {
        if (this.Items.Count == 0) return;

        if (DisplayMode == DisplayModeEnum.TextOnly || DisplayMode == DisplayModeEnum.TextAndImages)
            base.OnDrawItem(e);

        Category category = (Category)this.Items[e.Index];

        if (DisplayMode == DisplayModeEnum.ImagesOnly || DisplayMode == DisplayModeEnum.TextAndImages)
        {
            string imagePath = Path.Combine(IMAGE_FOLDER, category.ImageName ?? "");
            Image image = null;
            if (File.Exists(imagePath))
            {
                image = Bitmap.FromFile(imagePath);
            }
            else
            {
                imagePath = Path.Combine(IMAGE_FOLDER, IMAGE_NO_IMAGE);
                image = Bitmap.FromFile(imagePath);
            }

            // e.Bounds contain the area for the whole item. Text is 16 pixels high.
            Rectangle drawImage = new Rectangle(20, e.Bounds.Top + 12, 64, 64);
            e.Graphics.DrawImage(image, drawImage);
        }
    }

}